What is the legal test for admitting new evidence on appeal?

The test for the admission of new evidence on appeal is a stringent one. Writing for the Court in Palmer v. The Queen, 1979 CanLII 8 (SCC), [1980] 1 S.C.R. 759 at 775, Mr. Justice McIntyre set out the following test: (1) The evidence should generally not be admitted if, by due diligence, it could have been adduced at trial provided that this general principle will not be applied as strictly in a criminal case as in civil cases: see McMartin v. The Queen, 1964 CanLII 43 (SCC), [1964] S.C.R. 484. (2) The evidence must be relevant in the sense that it bears upon a decisive or potentially decisive issue in the trial. (3) The evidence must be credible in the sense that it is reasonably capable of belief, and (4) It must be such that if believed it could reasonably, when taken with the other evidence adduced at trial, be expected to have affected the result.